1. Field of the Invention
The present invention relates to a coin-type vibration motor mounted inside a mobile communication device such as a mobile telephone to be used as call-receiving means, and more particularly to a vibration motor capable of improving the assemblage efficiency of a connector header to maintain a securely fixed position.
2. Description of the Prior Art
In general, one of inevitable functions for a mobile communication terminal is a call-receiving function. The call-receiving function indicates call-receiving most frequently via a melody mode for producing sound and a vibration mode for shaking the terminal. In other words, if a user previously selects a mode necessary for call-receiving, the selected mode operates at the tie of call-receiving to allow the user to detect call-receiving.
In the above call-receiving modes, the vibration mode i s generally used for allowing others to keep from noise in a place crowded with people. In general, the vibration mode drives a small-sized vibration motor to transfer a vibrating force into a housing of the terminal so that terminal may vibrate.
In the meantime, a vibration mode conventionally in use is driven by a vibration motor which is additionally mounted inside the terminal. Examples of the most representative vibration motors include a so-called pan cake-type or coin-type vibration motor which has an external configuration with the diameter relatively larger than the thickness as shown in FIGS. 1 and 2.
A vibration motor configured as above is provided at the bottom with a plate-shaped lower housing 100 having a tubular burring section 100a which is projected for a certain height in a central section of the lower housing. The tubular burring section 100a has a shaft hole in the center so that the lower end of a shaft 140 is fixed through interference insertion. To the upper face of the lower housing 100 is attached a lower board 110 having a printed circuit to which external power can be applied and a terminal section 110a projectedly extended beyond an upper housing.
To the upper outer circumference of the lower housing 100 having the lower board 110 attached thereto as above, is provided a ring-shaped magnet 130 which has a vertically perforated space at the center and N and S poles alternatingly magnetized along the circular circumference thereof with the same interval.
In the lower board 110 provided under the perforated central space of the magnet 130, a pair of brushes 120 are spaced with a predetermined angle from each other, and have one ends respectively connected to input and output terminals of the lower boards 110 and the other ends positioned higher than the upper face of the magnet 130.
In the meantime, to the outer circumferential end of the lower housing 100 is coupled a cylindrical upper housing 150 for covering the lower housing 100 from the upside. The upper housing 150 is configured to axially support the upper end of a shaft 140 which has the lower end axially supported in the lower housing 100.
The shaft 140 supported to the lower housing 100, the lower board 110, the magnet 130, the pair of brushes 120 and the upper housing 150 constitute a stator in the vibration motor. A rotor 200 is installed rotatable about the stator, and comprises an upper board 210, a commutator 220 and wound coils 240.
The upper board 210 is a printed circuit board supported to the shaft 140 and a bearing b in an eccentrically rotatable fashion. The upper board 210 is integrally provided in a face opposed to the lower housing 100 with the commutator 220 constituted of a number of segments. For electric conduction, the segments contact to the upper ends of the pair of brushes 120 with the lower end connected to the lower board 110.
The wound coils 240 are attached to the upper face of the upper board 210 where a circuit is not printed. Although two wound coils 240 are provided as shown in FIG. 2, one wound coil may be alternatively provided due to a driving mode of the vibration motor. In particular, if at least two wound coils are provided, the coils are spaced from each other with a predetermined angle.
Further, the upper board 210 to which the wound coils 240 are not attached is integrally provided with an insulator 250 for insulation between the wound coils 240 and increase of eccentric load. Through insert injection, the insulator 250 is formed integral with the commutator 220 and the wound coils 240 which are attached to the upper board 210 during manufacture thereof. Between the adjacent pair of wound coils 240 is provided a weight having a high specific gravity for maximizing the amount of eccentricity.
The conventional vibration motor configured as above has a connector header 300 electrically connected to the terminal section 110a of the lower board 110. The connector header 300 has a substantially rectangular configuration with one circular face for closely contacting to the outer circumference of the upper housing 150.
The connector header 300 is attached to the outer circumference of the upper housing 150 via adhesive t, and constituted of a body 300a having an opened configuration at the upper and both sections and a pair of terminals 310 and 320 installed inside the body 300a. The terminals 310 and 320 have circularly bent structures so that the upper ends elastically project upward.
The conventional vibration motor configured as above is applied with electric current as the terminals 310 and 320 of the connector header 300 connect to an external system board (not shown). Current is induced into the commutator 220 via the brushes 120 of the lower board connected to the connector header 300. The commutator 220 transfers current into the wound coils 240 along the printed circuit on the upper board 210. Then, a magnetic flux generated from the wound coils 240 reacts with a magnetic flux generated from the magnet 130 to produce an electromagnetic force thereby rotating the rotor 200.
In this case, the rotor 200 is eccentrically supported to the shaft 140 so as to realize an eccentric drive. This causes an eccentric driving force to be transferred to the lower housing 100 and the upper housing 150 via the shaft 140 incurring vibration. This is utilized as silent call means of the mobile communication terminal.
However, in the above vibration motor of the prior art, the connector header 300 has the configuration to be simply fixed to the outside of the upper housing 150 via adhesive t. The connector header 300 may be easily played or detached from the upper housing 150 rather than maintaining a securely fixed position under external impact or dropping. Further, the terminals 310 and 320 which are mounted inside the connector header 300 and outwardly projected at one ends are not provided with any specific support structure. Thus, the terminals 310 and 320 may be easily deformed to cause contact defect under impact.
Accordingly the present invention has been made to solve the above problems of the prior art and it is an object of the invention to provide a vibration motor, in which a connector header is coupled to an outer face of a housing via welding to maintain a securely fixed position even under external impact or dropping.
It is another object of the invention to provide a vibration motor, in which terminals provided in a connector header can be restored to the initial positions even under external force to enhance the reliability of an article.
According to an aspect of the invention to obtain the above objects, it is provided a vibration motor comprising: a lower housing with a rim portion bent into the shape of a disk to form a flange; an upper housing inserted around the flange of the lower housing and covering an upper portion thereof to form an inner space; a lower board coupled to an upper face of the lower housing, the lower board having one end extended parallel beyond the lower housing to form a terminal section and an upper face connected to one ends of brushes; a magnet provided over the lower housing adjacent to an outer circumference of the lower board; an upper board rotatably supported to a shaft connecting between central sections of the lower and upper housings, and integrally provided at a lower face with a commutator selectively contacting to the brushes for electric conduction; a plurality of wound coils provided at an upper face of the upper board; an insulator made of resin provided at the upper face of the upper board for integrally fixing the wound coils and the upper board; a connector header provided in an outer face of the upper housing, and having terminals for applying external electric current to the terminal sections of the lower board; and a fixing bracket with a central section fixed in position inside the connector header and both ends bonded to the outer face of the upper housing via welding.
Preferably, the connector header comprises a fixing rib projected from a lower portion of the connector header toward a bottom of the lower housing and provided at one end with a fitting protrude which is elastically inserted into a gap formed between the flange of the lower housing and the inner circumference of the upper housing.
Preferably, the fixing rib is provided in plurality with an interval.
Also preferably, the fixing rib is integrally formed with the connector header via injection.
Preferably, the fixing bracket is bonded to the outer face of the housing via spot welding.
Preferably, the fixing bracket is made of sheet metal.
Preferably also, the connector header comprises: a pair of bilaterally symmetric terminals with one ends electrically connected to the terminal section of the lower board and the other ends forming elastic inserting sections which are bent projectedly in one lateral direction after upwardly extended and contacts extended again from the inserting sections and circularly bent upward; and a body for fixedly receiving the pair of terminals therein, the body having inserting grooves for elastically receiving the inserting sections of the terminals and connecting grooves provided at upper portions for connecting between the inserting grooves and the outside to outwardly project the contacts of the terminals.